Beekeeping is the maintenance of bee colonies, commonly in artificial beehives. Honey bees in the genus Apis are the most commonly kept species but other honey producing bees such as Melipona stingless bees are also kept. Beekeepers keep bees to collect honey and other products of the hive: beeswax, propolis, bee pollen, and royal jelly. Other sources of beekeeping income include pollination of crops, raising queens, and production of package bees for sale. Bee hives are kept in an apiary or "bee yard".